Black azo dye and process of making same.



IVAN LEVINSTEIN AND CARL MENSCHING, OF MANCHESTER, ENGLAND, ASSIGNORS TO THE LEVINSTEIN, LIMITED, OF SAME PLACE.

BLACK AZO DYE AND PROCESS OF MAKING SAME.

SFECIFICATION forming part of Letters Patent No. 654,167, dated July 24, 1900.

Application filed- January 17; 1900. Serial No. 1,763. (N specimens) To all whom it may concern.-

Beitknown thatwe,IvANLEv1NsTEIN,acitizen of the British Empire, and CARL MENSCH- ING, Ph. D., a citizen of the German Empire, both residing at Manchester, in the county of Lancaster,-- England, have invented certain new and useful Improvements in Black Azo Dyes and the Process of Making Same, of which the following is a full, clear, and exact description.

We have found that if acetyl-para-amidobenzene-azo-amido-alpha-naphthalene is diazotized and combined with naphthol sulfonic acids and the acetyl group is split off valuable azo dyes result,which dye wool in a neutral or acid bath deep-black shades which are fast to light and to washing.

To obtain these coloring-matters, we may proceed as follows: 304 kilos of acetyl-paraamidoben zene-azo-amido alphanaphthalene are suspended in three hundred liters of water containing seventy kilos of hydrochloric acid, (18 Baum.) The mixture is cooled down with ice to about 5 c'entigrade, and eight kilos of sodium nitrite are added with constant stirring. The thus-produced diazo compound is added to a solution of thirty-five kilos of naphthol salt R, sodium salt of betanaphthol disulfonic acid R, and forty-four kilos of soda or an equivalent molecular proportion of other suitable alkali. The immediately-formed azo color is heated to about 80 centigrade and is salted out and filtered oif. It is then dissolved in about one thousand liters of water and saponified in the usual known way to split off the acetyl group. After saponification the coloring-matter is salted out, filtered off, and dried.

The new coloring-matter is a black powder soluble in hot water withabluish-black color. It dissolvesin concentrated sulfuric acid (66 Baum) with a dullgreenish color, which changes to red on dilution and in an acid bath dyes Wool a deep-reddish black.

What we claim as our invention, and desire to secure by Letters Patent, is-

1. The process for the production of a black azo coloring-matter for dyeing wool, which consists in diazotizin g acetyl-para-amidobenzene-azo-amido-alpha-naphthalene, combining the diazotized product in an alkaline solution with naphthol disulfonic acid R, and in splitting off the acetyl group by saponification, substantially as set forth.

2. As a new article of manufacture, the new black azo coloring-matter which is de= rived from diazotized acetyl-para-amidobenzene-azo-amido-alpha-n aphthalene and naph thol disulfonic acid R, is a black powder soluble in Water with a reddish-blue-black shade, in concentrated sulfuric acid with a dullgreenish color which changes to red on dilution with water, is very slightly soluble in alcohol with a reddish-brown col0r,and which, in an acid or in a neutral saline bath, dyes wool a deep black.

In witness whereof we have subscribed our names to this specification in the presence of two subscribing witnesses.

IVAN LEVINSTE IN. CARL MENSCHING.

Witnesses:

WILLIAM GEO. HEYS, ARTHUR MILLWARD. 

